August 19, 1887.] 



SCIENCE. 



93 



tion. Tolerably complete discussions of some of the principal trials 

 of long-distance transmission are also included, together with some 

 of the numerical results of these trials. The volume contains much 

 that is interesting and useful to students of electricity, and will be of 

 undoubted value to those who are engaged in its practical applica- 

 tion. The American reader will look in vain for any account of the 

 more recent and highly important improvements in motors and sys- 

 tems of transmission which have originated in this country. This 

 will not be a matter of regret to any one who has secured a copy of 

 the next book under review. 



The Electric Motor and its Applications. By Martin and 

 Wetzler. New York, W. J. Johnston. 4°. 



Made up largely of articles contributed by its authors from time 

 to time to the Electrical World, by far the greater portion of this 

 \'olume is devoted to an exposition of the results of American ac- 

 tivity in this field. Again is found on the first page the usual cut 

 showing Oersted's experiment, and the usual brief and unsatisfac- 

 tory presentation of elementary principles, without which it seems 

 impossible for a book on electro-technics to make its appearance. 

 Not much can be said in favor of this well-nigh universal introduc- 

 tion. The reader has but to turn over a single leaf to find himself 

 involved in the use of such terms as ' counter-electromotive force,' 

 ' Lenz's law,' ' the law of Jacobi,' and many others, for the proper 

 understanding of which little assistance has been rendered in the 

 short study of ' theoretical principles.' Books of this class are writ- 

 ten for and read by those who already know more than the ele- 

 ments of the subject, and their presentation might safely be omitted. 



Two chapters are devoted to an account of the earlier experiments 

 with motors in Europe and America, and in the division of space 

 Europe gets five pages to America's sixteen. A chapter is given to 

 the theoretical consideration of the problem of the electrical trans- 

 mission of power, followed by a very short one on the electric rail- 

 way and tramway in Europe, and a very long one on the electric 

 railway and street-car lines in America. The use of storage-bat- 

 teries with electric motors on street-railway lines concludes the first 

 half of the book, the remainder of which is devoted to a considera- 

 tion of the industrial applications of electric motors in Europe and 

 America. Much the largest share of space is given to American 

 systems and inventions, and many of the most important ' plants ' 

 now in operation are described. The work is largely historical and 

 descriptive in its character, a scientific treatment of the subject be- 

 ing only attempted in a single chapter. 



As a resume of what has been thus far accomplished, especially 

 in this country, in the development of one of the most promising 

 fields of applied electricity, it will be found to be very interesting 

 and useful. Illustrations form a prominent feature of the work, 

 there being as many as two hundred, many of which occupy an 

 entire page. Several of the largest and most elaborate illustrations 

 are intrinsically of very little value, being merely ' pictures ' which 

 are in no way especially related to the real object of the work, and 

 convey no useful information. Of such may be mentioned a full- 

 page ' winter view ' of an electric street-railway, in which the only 

 thing suggestive of electricity is a possible lightning-rod upon a 

 building in the background. 



Electric Light Primer. By Charles L. Levey. New York, The 

 Author. 8°. 



This little primer consists of thirty-five octavo pages of good, 

 bad, and indifferent matter relating to the management of dynamos 

 and electric lights. The ' practical man ' here has full sway, and he 

 wisely declares in his preface that " it is not supposed that these 

 pages will be of any value to the electrician." 



They would have been of much greater value to the workmen 

 and engineer in charge of electric machinery if they had been pre- 

 pared by one who really understood what he was writing about. 

 As it is, a good deal of knowledge of the subject is required to 

 separate the good from the bad. 



The Storage of Electrical Energy. By Gaston Plante. New 

 York, Van Nostrand. 8°. 



The work before us includes the principal researches of Plante, 

 contributed to the French Academy, and various scientific periodi- 

 cals, from 1859 to 1879. The full history of the secondary batterj', 

 as it grew in his hands, will be found in the first two or three 



chapters, and the construction of various forms is given with great 

 exactness of detail. His use of the transforming rheostat for the 

 purpose of obtaining electricity of ' high tension ' is described at 

 length, together with many practical applications of this device. 

 The volume includes an account of Plante's experiments on the 

 nature of the electric discharge under high tension, and also his ap- 

 plication of these researches in the explanation of many natural 

 phenomena. 



While many electricians will be unable to agree with him in his 

 conclusions, all will be glad to find the results of his labor in so 

 compact and usable a form as that in which they are presented in 

 this volume. 



Electricity treated Experijnentally. By LiNN/EUS CUMMING-- 

 M.A. London, Rivingtons. 12°. 



Although an excellent little book, it will be something of a 

 disappointment to the many teachers and students who have for 

 several years made good use of the ' Theory of Electricity,' by the 

 same author. The disappointment will grow out of the fact that it 

 is a less complete and comprehensive treatment of the subject than 

 will be generally looked for. It contains the substance of a series 

 of experimental lectures given to senior boys in Rugby School, and 

 not much preliminary mathematical training is assumed. In a few 

 of the discussions a knowledge of mathematical principles as de- 

 veloped in the author's ' Theory ' is desirable, but in such cases the 

 fundamental formute may be taken for granted or the articles may 

 be omitted. Magnetism is first studied, and then a relatively large 

 space is devoted to frictional electricity. 



Book III. is devoted to voltaic electricity, and fills rather more 

 than one-half of the entire volume. At the end of each general 

 subject will be found an excellent list of problems and exercises \ 

 and, as the author says, the book is educational, and not technical, 

 in its plan and character. There are doubtless many courses of 

 study into which it will fit with extremely satisfactory results. 



Facts and Fictions of Mental Healing. By C. M. Barrows. 

 Boston, Carter & Karrick. 

 The writer of this book states that he has not himself been en- 

 gaged in mental healing, but has enjoyed exceptional facilities for 

 studying its operations, and investigating a great number and 

 variety of alleged cures. He is convinced by the results of many 

 careful tests, that, if the mental treatment of disease be not all that 

 its most sanguine advocates picture it, it is a powerful therapeutic 

 agent when skilfully used, and based on a philosophy which has 

 done the world incalculable good. In presenting the claims of this 

 method of treatment, he has tried to make it apparent that there is 

 a sound physical reason why well-directed thought should help the 

 sick as much as medicine does ; that a mental cure is nothing mys- 

 terious, but a natural event, which could not but take place under 

 favorable circumstances. He disclaims any desire to compel the 

 reader's assent, but his aim has been to awaken thought and 

 deepen the reader's interest by fairly stating the evidence both for 

 and against mental healing, and let him decide for himself. There 

 are facts that prove the possibility of such cures beyond a perad- 

 venture. There are fictions, also, which must be abandoned if 

 mental healing is to get and retain a hold upon the popular atten- 

 tion. It has a philosophy that will bear the intensest light that can 

 be thrown upon it ; and the subject needs only to be presented to 

 educated, thoughtful persons in the right way, to appeal to their in- 

 telligence and convince their reason. Under the title ' Mental Heal- 

 ing ' the author of this book includes ' spiritual healing,' ' prayer 

 and faith-cure,' ' metaphysical healing,' ' Christian science,' and 

 ' mind-cure.' In an introductory sun^ey, the wonderful reputed 

 cures are referred to of Dr. Newton, who, in Boston, in 1S59, re- 

 stored the sick to health by the laying-on of hands ; of Elizabeth 

 Mix, an ignorant colored woman of Connecticut, who performed 

 many faith-cures; of Dorothea Trudel, who, in 1861, in Switzer- 

 land, worked remarkable cures of cases given over by physicians as 

 utterly hopeless ; and of others which want of space will not permit 

 us to quote. The objection is often made to the various forms of 

 mental healing, that there is no positive evidence that the cures are 

 what they are claimed to be. Most of them, it is said, are performed 

 by persons unskilled in the science of pathology, and not qualified to- 

 judge whether the subjects of their treatment really suffer from the 



